significant relationship between the level of income and availability of land. There are, however, wide differences in urbanization and in output per capita and per hectare between the developed and developing countries. These differences contribute significant burdens on the natural environment. As Figure 2 shows, urbanization and high incomes are positively correlated. Both move up together, causing pollution problems to rise at a far greater speed then urbanization alone.
Population increase, particularly at the rapid rates now experienced by many less developed countries, makes an adequate response to these changes more difficult. Excess population and underemployment on farms rise not only because of improving farm technology but because of a rise in the total population. Urban populations rise under double pressures at rates sometimes as high as 10 percent per year, creating severe problems of planning, as well of capital accumulation to provide a decent living environment.
The last four columns of Table 3 show some indicators of particular types of pollution: fuel consumption as the principal source of air pollution; paper and board consumption as an indicator of solid waste problems; and fertilizer and insecticide use as an indication of land and water pollution arising from agriculture and health measures. Other indicators which might be used include wastes discharged into streams and lakes, scrap metal output, sulfur and other pollutants discharged into the air. Each of these specific indicators of pollution, as well as many others, is more or less closely associated with the two general indicators, population density and production.
In Figure 3 the relationship between GNP per capita and energy consumption is shown. The correlation is rather high, and the regression line is steep, showing that per capita energy consumption rises about fiftyfold for a tenfold increase in per capita GNP. Figure 4 shows a similar relationship between GNP and paper usage. Similar diagrams could be drawn, relating other specific measures of pollution to GNP per capita, population density, or some other aggregate. It seems clear from Figures 3 and 4 that rising income levels tend to add pressure on resourcesóboth in quantitative and qualitative terms-more rapidly than does increase in population. Yet we know that higher incomes also add to the ability to combat pollution and produce substitute materials.
CONCLUDING REMARKS ON RESOURCE POLICY AND MANAGEMENT
We have tried thus far to outline major trends and prospects for resource commodities and the natural environment under the impact of continued rapid population growth. We have traced this impact in quantitative and qualitative terms, recognizing from the outset that the two are closely interconnected in the real world. Our major attention has been on world regions and especially economically less developed areas.red to be incomplete.